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By S. Abe

Various copper anodes to be electrorefined were subjected to a heat treatment comprising annealing at a temperature in the range of 700 °c to 1,000 °c followed by a slow cooling preferably on the order of about 150 °c, and using these heat treated anodes , a series of dissolution experiments were conducted under conventional electrorefining conditions. The results obtained have indicated that the above annealing/slow cooling process dramatically improves the dissolution activity regardless of the type of anodes. As an example, passivation times of l to 3 minutes in a standard test have been increased to more than 80 minutes by this innovated heat treatment. Other advantages sterning from the improved anodic activity include reduced electrical short circuiting which results in substantial labor effort in the tankhouse, reduced energy requirement, and reduced cost of processing anode slimes because the amount of anode slimes is reduced. In addition, this process gives rise to a dramatic change in the nature of anode slime layer formed in such a way that a comparable final cathode copper product can be achieved even from high-impurity copper starting material.

Jan 1, 1987

By William K. Tolley

The U.S. Bureau of Mines (USBM) is investigating hydrometallurgical processing techniques to recycle metals from semiconductors and other advanced materials. Cadmium and tellurium were recovered from mixed CdTe/CdS scrap produced in the manufacture of thin-film photovoltaic devices. Cadmium and tellurium dissolution was achieved using hydrogen peroxide in dilute sulfuric acid. Leaching the scrap in 2.2 N H2SO4 yielded 99% Cd extraction and 98% Te extraction. Sulfur remained in the leach residue primarily in the elemental form. Elemental tellurium was precipitated from the leach liquor by adding Na2S2O5. Cadmium sulfate was recovered by evaporation. A preliminary process evaluation suggests that the process may have economic potential. Alternative recovery schemes are discussed.

Jan 1, 1995

By T. P. R. de Jong

Dual energy X-ray transmission imaging is extensively applied for safety luggage inspection. Its advantages are its rapid scanning rate (25 to 100 cm/sec) at approximately I mm resolution and simultaneous thickness independent metal identification. This is especially advantageous for secondary scrap metal inspection and automatic sorting. Other applications include metal product inspection, bale control, and waste processing. Recent progress in development of an automatic on-line sorter for bulk solids is presented and discussed. Besides various non-metal applications (solid fuels, wastes etc.) it appeared particularly effective in light metal sorting. As inspection tool better control of difficult to monitor solid bulk streams, batteries, bales and other related metals becomes possible.

Jan 1, 2003

By Jiang Feng, Zhang Libo, Peng Jinhui, Guo Zhanyong, Ju Shaohua, Lei Ting

The basics of microwave drying process of CuCl residue were studied by comparing the dielectric property of the residue with different moisture contents. The dielectric properties were measured by microwave cavity perturbation method. The dielectric constant and dielectric loss factor of the CuCl residue have a linear correlation with the moisture content. With this relationship, we can realize on-line measurement of moisture content of the CuCl residue by dielectric properties. The microwave drying experiments with different thicknesses (1-5cm) of CuCl residue were carried out, and the heating curve of the materials under different microwave powers (250-450W) was made. From these parameters, an optimized operation parameter of microwave roasting technology, the thickness of CuCl residue filter cake to be microwave roasted should be 2cm , was deduced.

Jan 1, 2015

By John E. Dutrizac, Tzong T. Chen

"Laboratory experiments were undertaken to ascertain the behaviour of various ""impurity"" species during the precipitation of hematite directly from ferric sulphate solutions at 225°C and in the presence of 40 or 50 g/L of hematite seed. Copper, nickel and zinc are not significantly incorporated in hematite precipitates. Although the nickel contents increase to 0.22% as the Ni concentration increases to 60 g/L, the solid solution Ni contents are low relative to the bulk Ni contents. Thus, part of the Ni may be present as tiny particles of poorly soluble NiS04.H20. Increasing germanium concentrations to 2,000 mg/L result in products containing up to 0.59% Ge. The Ge occurs either in solid solution in the hematite or is adsorbed on the nanometer-size hematite crystallites. Increasing As(V) concentrations to 10 g/L increase the AsO4 contents of the products up to 16%. However, the products consist of hematite together with As04-containing Fe(SO4)(OH) and an unknown Fe-AsO4 species. All the hematite products contain - 1% SO4 which appears to be adsorbed on the nanometer-size hematite crystallites.IntroductionDissolved iron is a common impurity in most hydrometallurgical processing circuits and, generally, the iron must be eliminated prior to the subsequent recovery of the sought after metals. Simple neutralization of iron-rich solutions yields slurries which are difficult to thicken and filter. To address these concerns, the jarosite, goethite and hematite processes have been developed, and these technologies are able to reject the dissolved iron in a readily filterable form [1]. Despite its higher cost, the hematite process offers several potential advantages. Because hematite is an iron-rich, high-density compound, its formation would reduce the mass of residue and the size of a residue storage pond. Hematite is the thermodynamically stable form of iron under ambient conditions, and this stability would facilitate the impoundment of hematite precipitates. Furthermore, hematite has some market potential for cement manufacture and even for iron making [2]. In all the commercial hematite processes, the dissolved ferric ions are first reduced to the ferrous state. Subsequently, the pH of the solution is adjusted and the solution is then oxidized. The ferric ions gradually generated during solution oxidation hydrolyze and precipitate mostly as hematite, although commercial hematite products also contain trace or minor amounts of jarosite-type compounds. However, there are potential advantages in precipitating hematite directly from ferric ion solutions, as the reduction and subsequent oxidation of the iron are not required. Although the precipitation of hematite directly from relatively concentrated ferric sulphate solutions (up to 0.5 M Fe(SO4)is) was recently demonstrated [3], the behaviour of impurity species during hematite precipitation is largely unknown. To address this issue, systematic laboratory experiments were undertaken to ascertain the behaviour of a number of ""impurity"" species during the precipitation of hematite directly from ferric sulphate solutions at 225°C, and the results are presented in this paper."

Jan 1, 2012

By K. Yarnaguchi

In the Mitsubishi Continuous Copper Converting Furnace, calcium femte slag is used. Due to its extremely high basicity, the improvement of corrosion resistance of the refractory lining is in need. In order to clarify the corrosion mechanism and to search for a new corrosion resistant material, first, the surface snuctures of bricks corroded in molten slags were observed by EPMA. Second, the dissolution behaviors of sintered MgO-based pellets containing various oxide additives were examined. It was found that the formation and the dissolution of magnesiofemte at the surface of the bricks play an important role in their corrosion and an addition of NiO, Mn02, or Ti02 to MgO is effective in stabilizing the magnesio-femte and improving the corrosion resistance of MgO.

Jan 1, 1994

By De-qing Geng, Guang-liang Wu

The waste slag generated by the LF refining process of Q345B low alloy hot-rolled steel, still has some refining capabilities. If recycled, it can reduce environmental pollution, and save the economic costs. A research on melting Characteristics of Q345B steel LF refining waste slag was investigated by using orthogonal experimental method, and the effect laws of composition on that were analyzed. Through variance analysis and significance criterion, it is concluded that the optimum ingredient of the regenerated LF refining slag is 25%A12O3, 12%CaF2, 7%MgO and R= (CaO)/ (SiO2) =2.5. And the regression analysis is carried out by using SPSS software, to get the mathematical relationship between ingredient with high reliability and melting temperature of refining slag T=1451.3-6.25CaF2+2.36 R.

Jan 1, 2016

By W. L. Dalmijn, J. M. Krowinkel

A recycling concept of end-of-life televisions starting with shredding will produce a complex material mixture, very heterogeneous in size, shape and degree of liberation. Basically all materials in television scrap are valuable, which means that recovery is important for either economic, environmental or sustainability reasons. However glass, plastics and metals are the materials with the highest potential for recovery. Non-magnetic materials from shredded television sets can be separated into three characteristic size fractions that need further separation for a high value-added recycling of the materials. This study investigated the potential of physical separation of these size fractions into valuable material streams using polyseparator, tlrldy current separator, dry and wet shaking tables and electrostatic separator. An overall mass balance of the mechanically processed televisions was calculated. Evaluation of the produced material fractions showed that heterogeneity in particle shape and size together with the presence of unliberated materials caused sever difficulties in separation when exclusively based on mechanical techniques. The results indicate that a certain degree of dismantling is necessary to achieve products of appropriate quality in physical separation. In order to improve recycling of electronic scrap through design for recycling cooperation between the electronics industry, the manufacturers and the recyclers of electronic goods is necessary.

Jan 1, 2000

By Juan Patricio Ibáñez

Separation of arsenic and copper from Cu-As-H2S04 electrolytes by electrodialysis has been investigated at room temperature. The effects of current density and pH were studied. An arsenic-free copper solution was obtained for all the tested conditions. The transport efficiency for copper ions was found to be higher than 98% after 3 hours' test. Transport of arsenic and copper through the ion exchange membranes was increased by increasing pH and current density. Solution pH was found to be a key parameter for the separation process, since it controls the speciation of the ions to be transported and the formation of unwanted precipitates which reduce the global efficiency of the electrodialysis process. The main conclusion is that electrodialysis is a promising technique to be used in separating and/or concentrating ions of interest in copper electrometallurgy.

Jan 1, 2003

By P. Lussiez

Precipitates consisting of amorphous ferrihydrite and crystalline goethite have been prepared by aging hydrolyzed Fe (III) solutions at room temperature. The precipitates have been characterized by x-ray diffraction and differential thermal analysis. The amorphous ferrihydrite transforms to goethite with time. The ferrihydrite to goethite transformation is affected by the presence of small amounts of copper or nickel coprecipitated with the iron. .The addition of copper decreases the amount of goethite at a given aging time and increases the amount of coprecipitate which is initially dissolved in sulfuric acid, but it does not seem to affect the dissolution of the crystalline part'. It is proposed that adsorption of copper hydroxo species on goethite nuclei delays the ferrihydrite to goethite transformation. The effect of nickel is less dramatic than that of copper. Apparently a portion of the added nickel is adsorbed on the goethite crystallite surface rather than incorporated into the goethite lattice.

Jan 1, 1981

By A. J. Paul, K. O. Yu

"Today, foundries are moving towards the use of models and design tools to gain a competitive advantage in producing castings of high desired quality. This leads to a growing alliance between foundries, software developers and researchers seeking to model, visualize and understand the phenomena taking place during the casting process. In addition, there is a need to develop affordable techniques to produce parts in small lot sizes. This leads to the development of a Flexible Manufacturing System consisting of: (1) up-front computer-aided engineering; (2) computer integrated proto typing with solid freeform fabrication; and (3) fabrication of the actual mold and related equipment to cast the part.This paper discusses some of the developments that are taking place today in the areas of modeling the physical phenomena during the casting process as well as towards developing a Flexible Manufacturing System for producing cast parts. Areas that require most work involve prediction of defects and mechanical properties using simplified analyses. In addition, electronic data sharing for collaborative engineering between geographically dispersed team members is also discussed. Case studies are presented showing successes as well as failures.IntroductionCasting, one of the oldest forms of metalworking, has recently seen a flurry of developments in the area of solidification modeling. These developments have come about after the realization that, in order to stay competitive, foundries need to reduce their scrap rate and production costs, and increase casting quality. Even though this is not new knowledge for foundry engineers, the tools to help them achieve this goal are just being developed and put in place for use by foundries. Several state-of-the-art software packages are currently available to analyze the solidification behavior in complex shaped castings. These packages make use of several different approaches for solving the various problems associated with casting processes. The overall architecture of a comprehensive solidification modeling system is shown in Figure 1."

Jan 1, 1994

By D. Raghavan

In recent years, the environmental issues related to the landfill shortage received considerable importance. Many polymeric solid wastes have high resistivity to chemical and biological degradation, and options are sought by which these wastes can be recycled and reused, or reduced in volume. The present study investigated the biodegradation of polyethylene by Aspergillus niger, and biodesulfurization of rubber by pure and mixed cultures of Thiobacillus thiooxidans and Thiobacillus ferrooxidans. The fungus, A. niger, was found to metabolize portions of polyethylene. Quantitative calorimetric measurements revealed that the amorphocity of the sample decreased during biodegradation. Removal of sulfur from synthetic rubber samples containing 2 to 15% sulfur, was studied in shake flask experiments and the associated oxygen consumption was studied in Warburg respirometers. The mixed bacterial cultures were more effective in the desulfurization of rubber samples than the pure cultures of T. thiooxidans and T. ferrooxidans. The data obtained in these studies may have far reaching consequence for the development of new effective processes regarding the remediation and management of discarded polymeric packaging wastes and car tire rubber materials.

Jan 1, 1993

By D. G. Mason

During the design of copper refinery tankhouses, there is a need to develop mass balance calculations for many process components, so that optimum physical plant configuration is achieved. Each mass balance is complex, possibly with over 120 interactive variables as basic input data. Recent developments in tankhouse design (e.g. permanent cathodes) have greatly increased the design options available for any project, multiplying even further the requirement for calculations. In the past these calculations were tedious and susceptible to human error. A comprehensive computer program can now simplify the task of the process metallurgist, enabling more sophisticated and sensitive plant designs to be produced. The paper describes the successful development of a flexible mass balance program that originallly was used in a feasibility study which had to be completed within a short time schedule. The program has been further developed and used for design and energy calculations; it can be usefully applied to existing plants to assess the impact of variations in operating parameters. The software takes account of staged liberation, electrolyte purification bleed and generates a reliable process inventory listing: it can also cope with stripper starting sheet options and disparate commercial circuits.

Jan 1, 1987

By Haydar Güneş

In this study, a hydrometallurgical process was evaluated for the recovery of Nd from a Nd-Fe-B magnet. Each leaching test was performed at the solid (weight) to liquid (volume) ratio of 1:50 and was mixed at 400 rpm at ambient temperature. The effects of 3 different acids (HCl, HNO3, and H2SO4) on the extraction of Nd were investigated and H2SO4 was found to be more effective than other acid solutions. Under the optimal conditions, pregnant leach solution was produced with H2SO4 for subsequent Nd precipitation testing. Each precipitation test was carried out using 100 mL of feed solution mixed at 600 rpm at 25°C. NaOH and H2C2O4 were used for Nd precipitation. The highest Nd was precipitated as Nd2(C2O4)3, 10H2O with C2H2O4 at 20 min.

By Osamu Takeda

A decomposition process for PCBs by using basic molten salts as a reaction field was investigated in order to establish a safe, simple and highly efficient decomposition process for polychlorobiphenyls (PCBs). PCB containing chlorine (e.g. 2, 2?, 4, 4?-tetrachlorobiphenyl) dissolved in n-nonane solution was supplied into basic molten salts (NaOH-Na2CO3 or KOH-K2CO3) maintained at 500-700 ?C together with the carrier gas (N2-21% O2) through an injection tube. The injected PCBs in a bubble are decomposed by the reaction with the molten salts and oxygen during rise in the molten salts. The decomposition efficiency of PCBs increased with increasing temperature and was achieved to be higher than 99.995% in a certain condition. From a series of systematic study, the effectiveness of the decomposition process for PCBs by using molten salts was demonstrated.

Jan 1, 2008

By T. Yoshida

The Ni-MH (nickel metal hydride) rechargeable battery was developed several years ago. Its higher electrochemical capacity and greater safety compared with the Ni-Cd rechargeable battery have resulted in very rapid Increase in its production. The Ni-MH rechargeable battery consists of Ni. Co and rare earth metals, so that recycling is important to recover these valuable mineral resources. In this study. a basic recycling process for used Ni-MH rechargeable batteries has been developed, in which the Ni. Co and rare earth elements are recovered through a combination of mechanical processing and hydrometallurglcal processing.

Jan 1, 1995

By Hiroyuki Matsuura, Fumitaka Tsukihashi

"Emission of CO2 gas from steelmaking industry covers more than 12 % of total CO2 emission in Japan. Though many efforts have been made to curtail energy consumption and high energy efficiency of Japanese steel production process has been achieved so far, further reduction of CO2 emission is strongly requested to develop sustainable steel production process and produce “green material”. Recently, authors have proposed the innovative hydrogen production process, in which water vapor is reacted with discharged steelmaking slag to produce hydrogen gas. This reaction can be achieved without any external energy source and operated by huge thermal energy associated with steelmaking slag and FeO or unrecovered Fe droplets that are relatively rich in the slag. In this paper, thermodynamic calculation results with various initial conditions in terms of hydrogen productivity were presented. Laboratory-scale experiments were also conducted to clarify the validity of thermodynamic calculation and the reaction rate in realistic conditions.IntroductionIronmaking and steelmaking process from iron ore through blast furnace and BOF is an essential steel production route for Japanese steel industries to supply high quality steel products in large quantity to society stably. Blast furnace – BOF process requires huge amount of fossil fuels such as mainly coal, resulting the emission of considerable amount of CO2 gas. Since the emission of CO2 gas from steel industries, about 147 Mt (FY2011), accounts for approximately 12 % of domestic CO2 gas emission in Japan (FY2011),[1] it is an urgent issue for steel industries to develop environmental-friendly ironmaking and steelmaking process and reduce CO2 emission. Various kinds of gases and by-products generated from ironmaking and steelmaking processes have been recycled as much as possible at present. Enormous thermal energy is also generated from processes and released to surrounding atmosphere as various forms such as sensible heats of gases, molten steels or by-products, and as heat losses. However, these energies are not utilized before final dissipation to atmosphere. Although various technologies to utilize thermal energy from ironmaking and steelmaking processes have been attempted to develop, practical application of these technologies has not been achieved because the thermal energy is not always useful as an energy source. In steelmaking process by BOF, fluxing agent such as CaO is added during reefing and thus about 100 kg/t-steel of steelmaking slag are generated. Since the steelmaking slag is discharged at temperature range between 1873 and 1923 K after discharge of refined molten steel, it also has large thermal energy. Amount of generated BOF slag is 11.0 Mt/y (FY2012) in Japan.[2] Assuming the amount of steelmaking slag is 10 Mt/y and its average heat capacity from room temperature to 1923 K is 1 kJ/kg·K,[3] unutilized heat is estimated to be 16 PJ/y, which is equal to annual energy consumption of 420 thousand families in Japan.[4]"

Jan 1, 2014

By Baohua Li, Yanhui Liu, Shengping Li, Xuewei Lv, Yun Chen

There are almost ten billion tons of vanadium-bearing titanomagnetite in Panzhihua-Xichang area. However, iron ores in Hongge, which has the most abundant reserves in the four mine areas in Panzhihua, have not been utilized sufficiently so far. The reason behind this is the relatively high Cr2O3 in the ores (0.49 %~0.82 %), that due to its high melting temperature will negatively influence the blast furnace reduction and slagging process. Therefore, in the blast furnace process, Cr is hope to be reduced into molten iron, which can reduce slag viscosity problems. Slag iron reduction experiments were conducted to quantify the Cr reduction. Experimental results shows that with the increase of TiO2, the content of Cr in the hot metal is decreased when balanced. And during the initial stage of the reduction reaction, the reaction kinetic model is a first-order reaction.

Jan 1, 2016

By Larry Twidwell, Ed Rosenberg, Courtney Young, Sean Dudley, William Gleason, Maureen Chorney

Experimental and industrially produced polystyrene and silica resins are tested for recovery capabilities of Rare Earth Elements (REE). Testing regimes being used are typical of resin analysis. Inductively Coupled Plasma-AES results indicate that preferential separation and recovery is possible in the adjusted pH range of2 to 10, solution conditions, and resin type. Testing conditions are resulting in structure modification of the composite resin as indicated by X-Ray Diffraction, Differential Scanning Calorimetry, Scanning Electron Microscopy, Mercury Porisometry, and density analysis. Resin modification indicates both surface and internal structure alteration outside of reported standard behavior of resins. Structural changes have ramification for both Rare Earth Recovery RER and traditional resin operations. Analysis shows that the resin uptake of REE can be manipulated for concentration. Further analysis with SEM work indicates that widespread surface and interior modification is taking place as resins load with REE. This modification is leading to pore rupture and particle breakage. Further investigation is being performed to determine the mode of breakage.

Jan 1, 2015

By S. Tandon

Equilibria studies of selenium distribution for sodium-borate slags were initiated at 1473k under reducing condition as a function of slag composition and alloy composition. The Se distribution coefficient (% Se in slag/% Se in metal) increased from 0.4 to 2.9 with increase in basicity (0.53 to 0.86) for Cu-0.446% Se alloy. However, the results are not very useful from industrial application viewpoint. Therefore, in order to improve the distribution of Se, CaO (10% to 50%) was added to the sodium-borate slag of basicity 0.864. On addition of 502 CaO, the distribution coefficient increased roughly by 100% for slag composition - 44.5% Borax, 22.2% Na2C03, 33.3% CaO and Cu-0.44677 Se alloy. Further, the value of this distribution coefficient has been found to increase by an additional 80% on addition of 20% CaF2 to the above slag for all Cu-Se alloy compositions. Also with increase in initial concentration of Se, the distribution coefficient has been noted to increase.

Jan 1, 1992